Most of the early books for children were didactic rather than artistic, meant to teach letter sounds and words or to improve the child's moral and spiritual life. In the mid-1700s, however, British publisher John Newbery (1713–1767), influenced by John Locke's ideas that children should enjoy reading, began publishing books for children's amusement. Since that time there has been a gradual transition from the deliberate use of purely didactic literature to inculcate moral, spiritual, and ethical values in children to the provision of literature to entertain and inform. This does not imply that suitable literature for children is either immoral or amoral. On the contrary, suitable literature for today's children is influenced by the cultural and ethical values of its authors. These values are frequently revealed as the literary work unfolds, but they are a means to an end, not an end in themselves. Authors assume a degree of intelligence on the part of their audience that was not assumed in the past. In this respect, children's literature has changed dramatically since its earliest days.

The fourth of the theories is as yet the least influential but seems to be gaining strength. Its key ideas are that human nature causes people to flourish more under some conditions than under others, and that social and political institutions should be organized to facilitate that flourishing. What, more specifically, are the conditions or “functionings” that enable people to flourish?